Dry chloridizing of ores



Patented Dec. 5 1933 UNITED STATES PATENT OFFICE DRY CHLORIDIZING 0F ORES Ralph F. Meyer, Freeport, Pa., assignor to Meyer I Mineral Separation Cpmpany, Pittsburgh, Pa., a corporation of Delaware No Drawing. Application May 4, 1932 Serial No. 609,334

17 Claims.

.This invention relates to the'chloridizing of metal values in oxidized orescontaining iron, and particularly to a dry process of absorbing various chloridizing gases in such ore at low temperatures to form ferrous chloride and thereby to chloridize accompanying metal values.

Various difliculties have interfered with the commerc'al chloridizing of ores by means of iron chloride as chloridizing agent. Thus, the ability to utilize ferrous chloride, during the actual chloridizing period, in many cases has been but momentaryand incidental, and such procedures in general have been wasteful of the reagent, and have provided only low yields of metal value chlorides. Some proposed processes of chloridizing metal values have included moistening an ore with solutions of iron chloride, but this is disadvantageous in that it requires separate preparation of the chlor'de, and it imposes difficulties both in handling wet ore and in the likelihood of decomposing the chloridized product by the effect of heatcombined with moisture. In some processes an amount of iron chloridemay be formed in ore containing iron when chlorine gas Is introduced to the ore, or when it is generated at high temperature from added chlorides, but here there usually is considerable loss of ferric chloride by volatilization. Also, the chlorine used is accompanied frequently by oxides of.su1fur, which tend to cause the presence of sulfates in the product, and suchcontamination is generally to be avoided in modern electrolytic treatments.

Another problem in chloridizing practice is to dispose. of waste gases, which may contain small amounts of free chlorine, various percentages of sulfur oxides, and frequently considerable amounts of ferric chloride. Though it is desirable to m'nimize the evolution 'of ferric chloride vapors from the ore, when they do escape it would be advantageous to reabsorb them directly in ore. Heretofore, direct absorption of ferric chloride vapor by ore has been so inefiicient that usually the chloride vapor has been subjected to intermediate treatment, such aschemical decomposition to obtain free chlorine.

Many chloridiz'ng processes, moreover, are objectionable because they involve high'temperatures that tend to destroy the chlorides sought and to leave a calcine of such physical and chemical nature that it is not readily amenable to subsequent steps of recovery.

It is among the objects of this invention to provide a dry process for treating ore directly with ferric chloride, chlorine, or other chlorinecontaining gases of miscellaneous nature, in

which such gases are absorbed and metal values I the ability to absorb chlorine and various chlorine, or chloride (e. g. HCl, FeCla, etc.) gases with great avidity and at very low temperatures, and that metal values may thereby be chloridized readily and extensively. Accordingly, this invention embodies a dry process of chloridizing oxidized ore bymeans of such active ferrous oxide and various chlorine-gases at elevated but relatively low temperatures, to form ferrous 'chloride, converting the latter, to ferric chloride, and causingchloridizing of metal values thereby.

In the practice of the invention the ferrous chloride formed in the'ore is converted to ferric chloride, and this may be accomplished bychlorine, or by air, or by water vapor, e. g. as dry steam. The ferric chloride mixture formed chloridizes the accompanying values, being thereby converted to inactive oxide and causing the liberation of chloride gases. much the same in the case of all of the agents The final products are referred to, but oxygen and steam require a longer time than chlorine to accomplish the desired result. The calcine produced contains chlorides of accompanying metals, is low in water soluble iron, and is of a physical character which is especially desirable for leaching.

In preparation for the practice of the invention ore is obta ned in oxidized condition. Naturally occurring oxidized ores are suitable, including not only oxides but oxidized salts, for example carbonates pr sulfates. roasted, preferably to oxides, to relieve subsequent steps of the burdenof removing the sulfur or similar element. The severaLsteps of this process are accomplished most effectively if the ore is in small particles, even as fine as 200 mesh. i

Ores of sulfide type are i Q preferred gases are carbonaceous, such as natural gas or, even better, producer gas and other gases containing carbon monoxide.

Some free metal may be formed during reduction, for example copper or nickel. fractory values also may remain, such, for instance, as arsenides, antimonides, or nickel sulfide. In the use of carbonaceous reducing agents, sulfates present in the ore are substantially decomposed, with removal of sulfur dioxide.

Ferrous oxide, as produced by the reduction, loses its extreme activity if exposed to oxidizing conditions at elevated temperatures, but it is stable at normal temperatures, and therefore the ore should be cooled in either neutral or reducing atmospheres until it is at normal temperature, or at least below approximately 150 C. This is accomplished suitably by passing a stream of neutral or reducing gas through or over the ore during cooling, to retain the active oxide and toremove any water vapor formed by reaction, as well as to exclude air. If desired, active ferrous oxide may be prepared separately, as described, and intimately mixed with ores to provide the amount of active oxide needed to chloridize the values.

The exact chemical formula of the active oxide is not certainly known to me, but the material is highly magnetic and is black in color, so that both ferroso-ferric oxideand simple ferrous oxide are within the scope of the term ferrous oxide as used herein. At the end of the chloridizing step now to be described the oxide in general becomes reddish, showing its conversion to the higher oxidized form.

In the practice of the invention the dry reduced ore containing active ferrous oxide is contacted with chlorine, with which the active oxide rapidly I and energetically combines to form ferrous chloride, and eventually ferric chloride, disseminated throughout the ore. The active-oxide also exhibits similar affinity for other chlorine gases, such as hydrogen chloride, and ferric chloride vapor. The ferrous chloride, under the influence of heat, advantageously combined with chlorine or with restricted amounts of a dry oxidizing gas, such as air or dry steam, then efiects profound chloridizing of the remaining metal values. Especially eflficient chloridizing results from the fact that the ferrous chloride exhibits substantially no tendency to volatilization at the temperatures used in the practice of the invention. Thus, it remains in the ore at temperatures up to 750 C., and because of this and its intimate distribution through the ore, it accomplishes exceptionally far-reaching attack of accompanying values.

The temperature used in this step will vary somewhat according to the ore undergoing treatment, but for most purposes it is preferred to have the ore between about 175 C. and 300 0., although the reaction between the activeoxide and chlorine does take place at lower tempera tures, for example at 150 C., or lower. The reaction also occurs at temperatures upward of 300 C., but two disadvantageous actions may be encountered. The avidity of the active oxide for chlorine is such that beyond about 300 0., and

in the absence of an oxidizing gas, it may be attacked in preference to metal values, and may even take chlorine from such compounds as cupric chloride. Moreover, high metal content materials, e. g. copper concentrates tend to become quite sticky and. agglomerate at such elevated temperatures. This renders them hard towork, andthe calcines become hard, de e and ill fitted for leaching. Below 175" C. copper forms cuprous chloride, which interferes with modern electrolytic treatments, and the action of ferric chloride is too slow to be attractive. Above 175 0., however, cupric chloride is formed and the reactions proceed rapidly. t

Most. advantageously this step is conducted between about 200 to 250 C. In this range the foregoing disadvantageous features are not encountered. Also, the energy of reaction of the chlorine upon the active oxide is such that it is feasible to operate at these temperatures without external heat, merely by regulating the rate of admission of chlorine to the ore. The avidity of the active oxide for chlorine is further shown by the fact that as long as active oxide is present no odor of chlorine'can be detected at the outlet end of the furnace.

Temperatures variant from those stated may beused, if desired, under particular circumstances. Thus, with copper absent lower temperatures may be used. Higher temperatures are desirable for. breaking down refractory compounds, such as arsenides and antimonides, and where the ore is not rich, or is appropriately dilutedwith an inert constituent, the stickiness referred to is not encountered; For such purposes temperatures up to, say; 750 C. may be used, as the ferrous chloride will remain in the ore up to suchtemperatures.

Accompanying the formation of ferrous chloride there may be a partial chloridizing attack of metals such as copper, gold, lead, nickel, etc. in the form produced by reduction. Chloridizing of the remaining values is effected by converting the ferrous chloride to ferric chloride and then to ferric oxide by means of chlorine or restricted amounts of air, or the like oxidizing gas. This may be done asa separate step in the manner presently to be explained, but it is accomplished most advantageously by simultaneouslytreating the ore with an atmosphere of chlorinecontaining gas containing controlled amounts of the oxidizing gas. This combines the two steps and offers. the further advantage that the iron chloride is converted to an insoluble inactive form, so that the aforementioned tendency to rob chloridized values of their chlorine is thereby repressed, thus making it possible to work at the higher temperatures if need be.

In other words, this step is conducted to effect formation of ferrous chloride and its continuous concurrent oxidation with attendant release of nascent, powerful chloridizing gases. Thereby the iron .is rendered insoluble and the accompanying values are extensively chloridized.

The air or other oxidizing gas is regulated so as not to oxidize the metal chlorides, and conveniently this is accomplished by restricting it to an amount such that the calcine retains some small amount of water-soluble iron chloride. This'protects the accompanying metal value chlo- -ride's.- From'about two percent down to traces loose, sandy and open nature, is readily permeable by leaching liquids, and is excellently adapt-I ed for further treatment to recover metal values,

either by leaching or by volatilization methods.

By suitably controlling the amount of oxidizing 1 gas used, the iron is substantially insoluble,'which Example I A copper sulfide concentrate containing iron and silica was self-roasted to a maximum temperature of 625 C. to remove sulfur. The roasted material was mixed with 8,-percent of coal and reduced at 625 C. in a muffle furnace and cooled out of contact with air. The reduced material contained 37.5 percent of copper and 18 percent of iron, together with silica and minor amounts of impurities. Considerable magnetic oxide was present in the reduced ore, showing the iron oxide to have been in a lower state of oxidation. Considerable metallic copper was also present in the reduced material.

The reduced product was treated with chlorine at a temperature of 225 C., the temperature being maintained evenly by regulation of the rate of chlorine admission, no external heat being required. During the treatment with chlorine no chlorine odor or fume was observable at the outlet end of the furnace, but after chlorine in an amount approximately equal to that theoretically necessary to combine with the copper to form cupric chloride had been absorbed the odor of chlorine at the outlet of the furnace became very strong. If the ore were fed into a furnace continuously no chlorine would be lost, as the absorption by the fresh incoming ore would be perfect.

The calcineassayed as follows:

Copper 37.41% soluble in water as cupric chloride.

Ferrous'iron 0.13% soluble in water.

Ferric iron 0.82% soluble in water.

This example shows the extremely high chlo-' ridization which may be obtained, together with a calcine of suitable physical characteristics.

Example I-A To show the effect of treating copper materials below 200 (3., another lot of the same ore was saturated with chlorine at 175 C. Assay of the calcine showed 92.5 percent of the total copper soluble in hot water. A considerable proportion of the soluble copper was in the form of cuprous chloride, but was soluble in "the hot cupric chloride solution, so that the solution would have to be treated to take care of the CuCl before electrolytic treatment. Also, the soluble iron was higher than in the preceding example.

Example I-B Another lot of the, same ore reduced as described in Example 'I was saturated with chlorine at 225 C. The temperature was then increased to 310 C. while continuing the chlorine stream. At about 300 C. chlorine was again rapidly absorbed, and at this time the ore became sticky relatively rich materials, and with attendant reduction in efliciency of chloridizing and increase in soluble iron.

Example I-C Another lot of the same reduced ore was treated with equal volumes of chlorine and air at 225 C. The calcine assayed 99.1 percent of the total copper soluble in water as'cupric chloride, and but 0.55 percent of iron soluble in water.

Example I-D Another lot of the same reduced material was treated with chlorine and a small amount of dry steam at 225 C. The calcine in this instance assayed 99.76 percent of the total copper soluble in water as cupric chloride, with 0.83 percent of iron soluble in water.

The foregoing examples illustrate the concurrent fixation of chlorine by the active iron oxide and its decomposition to effect chloridizing.

Example II A copper sulfide ore containing copper, iron, sulfur, silica, etc. was roasted and reduced at 625 C. with 3 percent of coal, followed by treatment with chlorine at 225 C. After reduction the material contained 7.25 percent of copper, of which 96.69 percent was rendered soluble in water by the chloridizing treatment. The calcine showed but 0.3 percent of iron soluble in water.

Example III A refractory sulfide ore of copper and nickel was self roasted to a maximum temperature of 600 C., followed by reduction at 625 C. with 5 percent of coal and cooling out of contact with air. The reduced material, which contained 1.15 percent of copper and 1.58 percent of nickel, was then treated with chlorine at 225 C. The calcine contained 99.14 percent of the copper as water soluble chloride, and 87.42 percent of the nickel as water soluble chloride.

In this instance the soluble iron in the calcine amounted to 2.14. percent.

' Example IV Anotherlot of the reduced material described in Example III was chloridized at 225 C, with equal volumes of chlorine and air. The calcine showed 81.52 percent of the nickel to be soluble in water, and 87.82 percent of the copper similarly soluble, while the soluble iron was reduced to 0.41 percent. This shows the benefit to be derived from the use of air in the chloridizing operation, to reduce soluble iron.

Some ores contain mineral values ofta persistently refractory nature, for example nickel sulfide. By the process of this invention, sulfide of this or other nature which may remain after roasting is largely eliminated in the dry treatment of absorbing chlorine, for instance in the mineral values by the ferrous chloride; I

quite undesirable. To overcome these difficulties a chloridizing salt, for instance calcium or sodium chloride, may be admixed with the ore after reduction in an amount corresponding to the small proportion of residual refractory sulfide, so that in the final stage of chloridizing under slightly oxidizing conditions inert sulfate is formed with corresponding return of ferrous chloride to participate in the process. If it is desired that the resulting sulfate be both inert during this chloridizing stage and also insoluble in subsequent extraction, the added agent may be calcium chloride, but otherwise chlorides of sodium or magnesium, for instance, are suitable.

Decomposition of the ferrous chloride may also be effected as a step separate from that of chlorine absorption, by treating the dry reduced ore with chlorine-containing gas under substantially non-oxidizing conditions, and after chlorine-absorption is complete heating with restricted amounts of air or the like The temperatures used in this step may be, and preferably are, those previously described, although temperatures up to about 550 C. may be used inparticular instances. The following examples are illustrative "of this embodiment of the invention.

Example V A sulfide ore containing 28 percent sulfur, 54 percent iron, and 3.80 percent nickel was roasted to remove the bulk of the sulfur, then reduced with natural gas at 600 C., and cooled in a stream ,of natural gas to normal temperature. Dry

N chlorine-containing gas was passed into the dry ore at 200 to 300 C. until about 7 percent of chlorine was absorbed, and the heat developed was sufficient to permit discontinuance of external heating, with the temperature of the ore rising from 200 to 325 C. The ore then was roasted with restriction of air for two hours at 300 0., there resulting a calcine containing 95.5 percent of the nickel in Water-soluble form, and but 0.33 percent water-soluble iron.

About 1.5 percent of calcium chloride in finely ground condition was added to the ore to convert to ferrous chloride any ferrous sulfate that might form during the chloride roasting.

Example VI A sample of mixed oxide-sulfide copper ore containing 2.9 percent of copper was given a quick roast to remove. sulfur, reduced at about 600 C. with natural gas, and then contacted at about 200 to 300 C.'with chlorine-containing gas to absorb about 5 percent chlorine, after which it was ,subjected to a final chloridizing roast with restriction of air. In the calcine 97.6 percent of the copper was water soluble.

In' some instances in practicing this latter embodiment the efficiency of absorption may be increased by including a small amount, of reducing gas with the chlorine-containing gas. The reducing gas is not to affect the solids in the ore, but to neutralize any small amounts of oxygen present in the chlorine-containing gas. Likewise it may be advantageous to reduce ore as described, to form active oxide, then absorb the chlorine-containing gas, and then repeat reduction of the ore and subsequent absorption of chlorine gases. This simply rectifies any accidental oxidation of the active oxide. But by the inclusion of a small amount of reducing gas with the chlorine gases, alternation of treatment is avoidable, and this embodiment is readily prac ticed at temperatures of 350 to 500 C.

Example VII The invention is applicable also to the chloridizing of precious metals at low temperatures. Thus an ore containing gold, silver, cobalt, copper, about 20 percent of sulfurfand about 10 percent of arsenic was roasted to remove sulfur and arsenic. It was then reduced at 625 C. with 3 percent of coal and cooled out of contact with air, followed by treatment withchlorine at 225 C. The calcine was then leached with an 8 percent copper solution made by leaching successive lots of material. The results were as In this instance the metal content vwas so low as to leave considerable iron soluble, there being not enough metal values to which. the iron chloride could give up its chlorine. .By continuing the chlorine treatment the soluble iron can be reduced, however.

Gaseous reducing agents possess some advantages over solid combustibles in the initial reduction stage. For instance, it is difiicult to entirely eliminate solid admixed reducing agents, such as .coal, and they carry over through the chlorine absorption stage to the final stage of chloridizing by transfer of chlorine in the presence of oxygen from the ferrous chloride. In this final chloridizing step, such residual carbon may act on the'iron oxide formed to reconvert some portion of it to its active form, and the great aflinity of this active ferrous oxide for chlorine may then destroy some portion of the other metal chlorides and reconvert them to inpractical importance is the utilization of what have been regarded heretofore as waste gases. Thus, gases leaving the ore during the chloridizing stage may carry some amount of ferric chloride, or from oxidation of residual sulfides they may carry sulfur dioxide, and in some instances there will be also some content of hydrogen chloride or free chlorine. Such gases usually will be of low concentration, but in the aggregate cause waste of considerable valuable reagent, or lower the yield of chloride, and heretofore their recovery has been difficult and uneconomical. In this process such waste gases are recovered by passing'the gas into contact with dry ore containing active ferrous oxide. Theactive oxide abstracts the chlorine-gases readily and substantially completely, even at low temperature, to form ferrous chloride, but does not abstract sulfur dioxide in a dry atmosphere. Under nonoxidizing conditions even the ferric chloride is absorbed quickly, while sulfur dioxide is eliminated. Upon raising the temperature to 175 C., or higher, chloridizing decomposition sets in,

1 as described hereinabove.

what has been said the purposes of this invention the term chlo-' duced material With the process conducted in conventional rotary kilns, as it preferably is, there is effective utilization of low temperature heat and desirable flow of materials is carried on readily to protect the active oxide from oxidation. Thus from waste gases chloridizing agents are abstracted simply and effectively, and a gas having both a chlorine content and a content of sulfur dioxide is purified by abstraction 'of the chlorine content in the ore.

In this process the efficiency. of recovery is high, and the range of materials amenable to the treatment is extensive. Low grade and complex ores, concentrates, refractory materials, and the like are within its scope. Moreover this process is available for special uses, as for removing impurities from iron ore to beneficiate it, i. e. to obtain purified iron 'oxide, or to remove and/or recover impurities, such as phosphorus, present in small amount or in refractory condition from ore of high iron content.

In this description and claims iron is referred to in illustration of what may be termed a reagent metal, by which is meant a metal capable of existing in its compounds in conditions of higher and. lower valence, or in ic and ous conditions. For example, copper, iron, nickel andmanganese form oxides of lower valence, and under the conditions of this invention these oxides are obtained in active form and utilized for extracting metal compounds from their ores.

In illustration of this invention reference has been made particularly to the absorption of chlorine gases in ore containing active ous oxide of reagent-metal, but other acidic gases are absorbed similarly and thus utilized for attacking mineral values. For example sulfur trioxide' is absorbed by dry, active ferrous oxide under neutral conditions, to form metal compoundawhich may be extracted or may be utilized further for attack of accompanying materials. And from it will be understood that for rine gases comprehends equally free chlorine, hydrogen chloride, ferric chloride, and the like gases which react with active ferrous oxide to form ferrous chloride.

This application is a continuation in part of my copending application, Serial No. 555,366, filed August 5, 1931.

- According to the provisions of the Patent Statutes, I have explained the principle and oper ation of my invention, and have described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. A process of chloridizing metal values in oxidized ore containing iron, comprising heating the ore under reducing conditions to form active ferrous oxide therein, and treating the dry recontaining said active oxide between 100 C. and 750 C. with chlorine-containing gas and thereby forming ferrous chloride and effecting chloridizing attack of metal values and forming a loose permeable calcine containing said chloridized values and containing the iron substantially completely in insoluble oxide form.

2. A process of chloridizing metal values in oxidized ore containing iron, comprising heating the ore at between 400 and 700 C. under reducing conditions to form active ferrous oxide therein.

treating the dry reduced material containing said active oxide at between 150 C. and 300 C. with chlorine-containing gas to form ferrouschloride in the ore and thereby effecting chloridizing of metal valuesand forming a loose permeable calcine containing chloridized values and containing the iron substantially completely in insoluble oxide form.

3. A process of chloridizing metal values in oxidized .ore containing iron, comprising heating the ore with a carbonaceous combustible reducing agent to form active ferrous oxide in the ore,

treating the dry ore containing said active oxide C. with a chlorine-conat about 150 C. to 300 taining gas to form iron chloride in the ore, and decomposing said chloride in the ore, and-thereby chloridizing metal values and forming a loose permeable calcine containing the chloridized values and low in soluble iron.

4. A process of chloridizing metal values in oxidized ore containing iron, comprising heating the ore with a carbonaceous agent to form active ferrous oxide in the ore, treating the dry ore containing saidact'ive oxide at about 150 to 300 C. with an atmosphere containing'chlorine and containing an oxidizing gas restricted in amount to decompose in the ore the iron chloride formed therein, and thereby chloridizing the'metal values in the ore and forming a loose permeable calcine containing the chloridized values and low in soluble iron.

5. A process of chloridizing metal values in oxidized ore containing iron, the ore with a carbonaceous combustible reducing agent to'form active ferrous oxide in the ore, treating the dry ore at about 150 to 300 chlorine-containing .gas and air restricted in amount to decompose in the ore the iron chlorideformed therein, and thereby chloridizing the metal values in the ore and forming a loose permeable calcine containing the chloridized values and low in soluble iron.

6. A processof chloridizing metal values in oxidized ore containing iron, comprising heating the ore with a combustible carbonaceous reducing'agent between 250 to I50" C. to form active ferrous oxidein the ore, cooling the ore under substantially non-oxidizing conditions, and treating the dry ore containing said active oxide at about 150 to 300 C; witha chlorine-containing gas to form ferrous chloride and chloridize metal values in the ore, and decomposing excess iron chloride in the ore with a restricted amount of a dry oxidizing gas, and thereby forming a loose permeable calcine containing metal value chlorides and low in soluble iron.

'7. A process of chloridizing metal values in oxidized ore containing iron, comprising provid ing active ferrous oxide inthe ore, and treating the dry ore containing said oxide with a chlorine-containing gas to form.iron chloride in the ore, and during said treatment decomposing said chloride in the ore with-a restricted amount of air, and thereby chloridizing metal values and forming a loose permeable calcine containing the chloridized values and low in soluble iron.

8. A process of chloridizing metal values in oxidized ore containing the pm under reducing conditions to form active ferrous oxide, cooling the-ore under substantially non-oxidizing conditions, treating the containing said active oxide with a chlorinecontaining gas at a temperature of 100 to 750C. to form ferrous chloride in the ore, and then heating the ore at a temperature of 175 C. to

containing said active oxide 'j C. with an atmosphere of' combustible reducing comprising heating iron, comprising heating dry ore 500 C. to decompose iron chlorides therein and thereby chloridize metal values and form a calcine of loose permeable character containing the chloridized values and low in soluble iron.

9. A process of chloridizing metal values in 'oxidized ore containing iron, comprising heating the ore with a combustible carbonaceous reducing agent to form active ferrous oxide in the ore, treating the dry ore containing said active oxide with a chlorine-containing gas under substantially non-oxidizing conditions at a temperature of 150 to 300 C. to form iron chloride in the ore, and heating the thus-treated ore at about 150 to 300 C. with a restricted amount of air to decompose said chloride therein and thereby chlo= values and low insoluble iron.

10. A process of beneficiating oxidized iron ore, comprising reducing the ore under dry, non-oxidizing conditions with carbonaceous material at a temperature between 250 and 750 C. to form active ferrous oxide therein, cooling the ore under substantially non-oxidizing conditions, contacting the d y l duced ore containing said active oxide at a temperature of 150 to 550 C.

with chlorine-containing gases to form iron chloride, and decomposing iron chlorides therein with a restricted amount of air to chloridize metal values and thereby form a loose permeable calcine containing chloridized values and less than about two percent of water-soluble iron.

11. A process of chloridizing metal values in oxidized ore containing iron and refractory sulfide, comprising reducing the ore with carbonaceous material at about 400 to 700 C. to obtain active ferrous oxide, cooling the ore under substantially non-oxidizing conditions, treating the active oxide at 200 to 500 C. with chlorine-containing gases to form ing chloridized values and low in soluble iron.

12. A process of chloridizing metal values in oxidized ore containing iron, comprising reducing the ore with carbonaceous material at 250 active ferrous oxide, treating the dry ore containing said active oxide at 150 to 300 C. with a chlorine-containing gas to form ferrous chloride in the ore, then oxidizing the ferrous chloride in the ore under slightly oxidizing dry conditions to chloridize accompanying mineral values, withdrawing from the,

ore the waste gases containing ferric chloride and absorbing the ferric chloride under non-oxidizing conditions with dry reduced ore containing active ferrous oxide.

- tive reduced ferrous oxide to 13. A processof chloridizing mineral values in oxidized ore containing iron, comprising reducing the ore with carbonaceous material at 250 to 750 C. to obtain active ferrous oxide, maintaining dry, non-oxidizing conditions to preserve the active oxide while heated, and heating-at 200 to 500 C. with a gaseous mixture containing ferric chloride to absorb the ferric chloride and form ferrous chloride in' the ore, and then heating the ore under slightly oxidizing conditions to decompose iron chlorides and chloridize accompanying mineral values.

14. In a process of chloridizing metal values in oxidized ore containing iron, the stepscompassing chlorine or gas into contact with the convert said oxide to ferrous chloride, and regulating the rate of chlorine addition so that the heat liberated by reaction chlorine on the ore maintains the ore at between about 150 to 300 C.

15. In a process of chloridizing metal values in oxidized ore containing iron, the steps comprising passing chlorine or a reactive chloride gas into contact with the dry ore containing active dry ore containing ac-- reduced ferrous oxide and thereby converting.

said oxide to ferrous chloride, oxidizing said chloride to the ferric state in the ore and effecting chloridizing of metal values thereby, andregulating the rate of addition of chlorine to maintain the ore at between 150 and 300 C. by the heat of reaction of said chlorine and active ferrous oxide.

16. In a process of chloridizing metal values in oxidized ore containing iron, the steps comprising heating the ore with a carbonaceous reducing agent to reduce the iron to active ferrous oxide, cooling the treating the dry ore containing said active oxide with a chlorine-containing gas at a temperature of about 175 to 300 C. to form iron chlorides in the ore, decomposing said chlorides in the ore and thereby effectingchloridizing of metal val- ,ues, and during treatment with said chlorine- RALPI-I F.VMEYER.

ore with exclusion of oxygen,

process of chloridizing metal values ore containing iron, the steps com-. 

